This invention relates to an improvement in burner design and performance for use in the manufacture of gaseous mixtures comprising H.sub.2 and CO such as synthesis gas, fuel gas, and reducing gas by the partial oxidation of pumpable slurries of solid hydrocarbonaceous fuels in a liquid carrier or liquid hydrocarbonaceous fuels.
Annular type burners have been employed for introducing feedstreams into a partial oxidation gas generator. For example, in co-assigned U.S. Pat. No. 5,261,602, an improved burner of the "hot tip" design using a porous ceramic tip is employed in such a system. Such burners are used to simultaneously introduce the various feedstreams into the partial oxidation reactor. Single, double and triple annulus burners are shown, for example in co-assigned U.S. Pat. No. 3,528,930; 3,758,037; and 4,443,230, respectively, for the introduction of plural feedstreams into such systems.
In the use of such burners in pumpable slurry mixtures of hydrocarbonoaceous fuels in a liquid carrier or in the use of certain liquid hydrocarbonaceous fuels, a problem that is most often encountered when working with high ash feeds is the problem of slag deposits on the burner body. Such deposits create unstable gasifier operation. A slag deposit forms on the burner body and grows until it interferes with the burner spray pattern of fuel and free oxygen containing gas. This results in increased and fluctuating carbon dioxide and methane levels in the produced gas and causes the gasifier temperature to rise to the point where the gasifier must be shut down for safety reasons. Some particularly "dirty" feeds can have a particularly exacerbating effect on this problem. One such feed comprises coal and dirt with 30% to 40% of the solids as ash (i.e. inorganic) in a water slurry.
Such burners come into contact with recirculating gasses in the interaction zone that contact the outer surfaces of the burner. These gasses can have a temperature in the range of 1700.degree. F. to 3500.degree. F. Burners are cooled to withstand these temperatures by means of cooling channels through which a liquid coolant such as water is passed. Cooling coils are wrapped over the exterior surfaces of the burner along its length. Also the use of an annular shaped cooling chamber has been used to provide additional cooling at the burner face. Because of the heat flux from the radiant gasifier to the burner face, and through the burner face into the cooling liquid, thermal stress cracks can develop in the metal near the tip of a burner. These cracks can lead to flow modifications in the various feedstocks that can completely disable the burner.